Angled Orthopaedic Milling Cutter for Precise Bone Seat Access
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Solution Overview
Problem
Existing milling cutters for orthopaedic surgery, particularly in knee and ankle operations, face challenges such as increased bone removal, non-uniform cement distribution, and structural complexity, making them difficult to handle and obstructive to the surgeon's view, with limited access due to the proximity of the femur.
Innovation Solution
A milling cutter with an angled operating head and gimbal joint, featuring a tubular envelope with overlapping half-shells and anti-rotation elements, allowing the tool axis to be inclined relative to the longitudinal axis, facilitating access and reducing bone removal while maintaining ease of handling and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the milling cutter tip is mounted on a gimbal joint to allow angled axis of action, then access to the tibia is improved, but the device complexity increases and is not appropriate for knee operations
Solution Approach 1:
The milling cutter is divided into separate functional segments: a handle portion, a shaft, and a cutting head that can be independently positioned. This segmentation allows the cutting head to be angled relative to the shaft without requiring a complex gimbal joint, as each segment can be optimized independently for its specific function.
Solution Approach 2:
The patent introduces angular positioning capability in a different dimensional approach - by allowing the cutting head to be positioned at various angles relative to the shaft through a simplified mechanism, rather than using a full gimbal joint system. This provides the necessary angular access while maintaining structural simplicity.
2Productivity
If a milling cutter tip is used to create a seat for stability element, then the operation can be performed, but increased bone removal occurs and cement tightness decreases
Solution Approach 1:
The cutting head is designed with specific local geometries that concentrate the cutting action precisely where needed - the V-shaped configuration allows for focused bone removal only in the immediate seat area, rather than broader removal. The angled sides of the V-shape direct the cutting force locally to create a precise fit for the stability element.
Solution Approach 2:
The patent employs variable angle configurations in the V-shaped cutting head, where the angles can be adjusted or selected to optimize the cutting geometry for different bone densities and seat requirements. This parameter optimization allows for minimal bone removal while achieving the desired seat geometry for optimal cement distribution and tightness.
Data Source
AI summary
An orthopaedic surgical instrument, in particular a milling cutter, including: an inner rod extended along an own longitudinal axis and provided with an attachment end to a motorized member; a tubular envelope wrapping the inner rod; an operating head at a rod end which is opposite said attachment end; a gimbal joint between the rod end and a tool of said operating head such that said tool is extended along an angled axis with respect to the longitudinal axis. The milling cutter according to the invention improves the precision of execution of the positions of the holes in any surgical operation with anatomy which is difficult to get access to, such as in knee, pelvis and ankle.